You can cut coils off the spring and get it down to about 3-3.5 lbs and it ain't bad.

Better than that is a Rifle Basix Sav-1 aftermarket trigger for about $80-100. Very nice hunting trigger. I don't know if a Timney will work in the Axis, I suppose it will. Same idea.

I have tried those springs you mention, they aren't anything special, by any means. Certainly no better than cutting the coils down.